Traumatic benign paroxysmal positional vertigo caused by cannon fire

Abstract

Benign paroxysmal positional vertigo (BPPV) is the most common cause of vestibular vertigo. BPPV is characterised by brief episodes of vertigo that occur with movement of the head. Almost a quarter of cases of BPPV have a traumatic cause, but no cases of traumatic BPPV due to indirect trauma were found in the English literature. A 37-year-old woman presented for episodic vertigo that occurred with position change, which started after she was exposed to cannon fire. She had a positive hallpike which confirms the diagnosis of BPPV. Her BPPV was successfully treated using the Epley manoeuvre. The diagnosis of BPPV is made from a careful history and physical exam. Traumatic BPPV can occur with indirect trauma such as being downrange during cannon fire. The treatment of both idiopathic BPPV and traumatic BPPV is with canalith repositioning procedures.

Background

Benign paroxysmal positional vertigo (BPPV) is the most common cause of vestibular vertigo, with a 1-year incidence of 0.6%, a 1-year prevalence of 1.6% and a lifetime prevalence of 2.4% (3.2% in women and 1.6% in men).¹ A small portion of BPPV is related to head trauma, with one study suggesting 8.5% of BPPV cases presenting to a neuro-otology outpatient clinic were post-traumatic.² In that series, 57% of cases were related to motor vehicle crashes, with half of the patients suffering whiplash injury. Other causes of post-traumatic BPPV in the series included falls, blows to the head, ventriculoperitoneal shunting, a violent speedboat trip, removal of occipital osteoma and dental surgery. Another study found that 23.4% of patients with BPPV had a traumatic cause, with the vast majority involved in motor vehicle accidents, with 28% after accidental falls and the rest with intense physical activity, after sinus floor elevation, following postural gymnastics, and in bedridden patients.³ Literature also shows cases of post-traumatic BPPV from falls off camels⁴ and in hunters and skeet shooters.⁵ For those firing long guns, BPPV was found ipsilateral to the side where the gun rested on the shoulder and is felt to be related to the whiplash from gun recoil.

Case presentation

A 37-year-old woman with a medical history significant only for recurrent migraine headache treated with propranolol and amitriptyline presented with vertigo with changes in position. The patient had no family history of neurological conditions. She was married and worked full time. Her symptoms started 4 days prior to her presentation. She was attending a Civil War re-enactment and was standing about 30 ft away from a cannon when it was fired (without shot). The patient had a sudden onset of dizziness and some headache when the cannon fired. She had ongoing brief episodes of vertigo with movement of the head or rolling over and nausea, but no vomiting with the vertigo. The patient denied any tinnitus or hearing loss. She did not have any ear pain and no fever, chills or other systemic symptoms. She had no history of episodes of vertigo.

On examination, the patient was alert, oriented and uncomfortable, but in no significant distress. She felt a little unstable at times, but generally, gait was stable. Her pupils were equal, round and reactive to light, and extraoccular muscles were intact. The patient’s external auditory canals were clear, and tympanic membranes were clear and intact. Her cardiac, respiratory and abdominal exams were unremarkable. The cranial nerve exam was normal. The patient had normal strength in all major muscle groups and normal reflexes. She had a positive hallpike to the left, which confirmed the impression of BPPV, in this case affecting the left posterior canal.

Differential diagnosis

This patient’s diagnosis of BPPV was clear from her history and examination; however, the differential diagnosis for vertigo includes labyrinthitis, vestibular neuritis, cerebellar/brainstem infarction/haemorrhage/neoplasm, vestibular migraine, vertebrobasilar insufficiency and vertebral artery dissection.

Outcome and follow-up

A canalith repositioning procedure (Epley manoeuvre) was performed on the patient with a very significant reduction in her symptoms. Other than some nausea during the procedure, she experienced no adverse effects from the treatment. The patient was instructed to repeat the procedure at home if needed. The patient has not had any recurrences of vertigo in a year of follow-up.

Discussion

In this case, the patient’s history makes it clear that the cause of her BPPV is the close exposure to cannon fire. While a literature review shows post-traumatic BPPV related to a variety of whiplash injuries and direct blows to the head, a search of the English literature does not reveal cases of BPPV from non-contact forces such as cannon fire.

Post-traumatic BPPV is treated the same as idiopathic BPPV, with canalith repositioning procedures such as the Epley manoeuvre for posterior canal BPPV. For clinicians and patients who are not familiar with canalith repositioning procedures, video-sharing sites such as YouTube contain videos that accurately demonstrate how to perform these manoeuvres.⁶ Current guidelines recommend against postprocedural postural restrictions after canalith repositioning procedures and recommend against the use of vestibular suppressant medications such as antihistamines and benzodiazepines for most patients with BPPV.⁷

A diagnosis of BPPV can be made from a careful history and physical exam. A significant portion of BPPV cases are related to trauma; while most reported cases are related to motor vehicle crashes, traumatic BPPV can occur even with indirect trauma, such as being downrange during cannon fire. The treatment of both idiopathic BPPV and traumatic BPPV is with canalith repositioning procedures such as the Epley manoeuvre.

Patient’s perspective.

I thought that the cannon might cause a migraine but was surprised that the cannon caused vertigo. The vertigo occurred instantly when the cannon fired. The vertigo felt like being on a carnival ride. With the repositioning procedure, the symptoms immediately and completely went away. I have not had any more vertigo since.

Learning points.

• Benign paroxysmal positional vertigo (BPPV) is a common condition that is sometimes associated with trauma.

• Post-traumatic BPPV can occur even without direct head trauma.

• Generally, vestibular suppressant medications should be avoided in the treatment of BPPV.

• Although post-traumatic BPPV can be more difficult to treat, all cases of BPPV should be treated with canalith repositioning procedures such as the Epley manoeuvre.